Trailer brake actuator



Feb. 9, 1965 J. 0. Ross ETAL 3,168,940

TRAILER BRAKE ACTUATOR Original Filed July 13, 1959 war.

JAMES 0. E055 CLMENTJ. SMITH BY 'Jllff THE/E l7 7'TOEIVE'YS United States Patent Ollice Bdhhfiti) Patented Feb. 9, 1965 3,168,940 TRAILER BRAKE AETUATUR James 0. Ross, Fort Myers, Fla and Clement J. Smith,

Vandalia, @hio, assignors to Toledo Stamping d; Manut'acturing Company, Toledo, (lhio, a corporation of Ohio Continuation of application Ser. No. 826,821, July 13,

195. This application Aug. 22, 1962, Ser. No. 21%,794 ll fllaim. (El. 183-112) This invention relates to a novel automatic trailer brake actuator. More particularly, this invention relates to a novel control means for a brake actuator of the type that is operated by the momentum of a trailer when overtaking its towing vehicle, as a result of the towing vehicle coming to a stop or when the two vehicles are going down a hill. The towing vehicle may be an automobile, a truck, a tractor or the like. It will be clear from the following disclosure that this invention may be used in many types of towing devices and is not limited to towing devices for trailers.

Various automatic trailer brake actuating devices are known of the type having hydraulic mechanisms operated by relative movement between the trailer and the towing vehicle. Usually, provision is made for relative movement between the trailer tongue and a tow bar attached to the towing vehicle. In some of these devices, a hydraulic piston rod ou -the trailer tongue is struck by a part of the two bar mechanism, thereby actuating a hydraulic actuator mechanism also located on the tongue.

While prior art devices shown various types of actuators, it has been found that an improved actuator having a more positive action results by pivoting the piston rod directly to the tow bar. Thus, the hydraulic cylinder and piston are located on the tongue and the piston rod is located on the tow bar. By providing a simple adjusting device at the piston rod pivot, it is possible to accurately adjust the response characteristics of the brake actuator.

The primary object of this invention is to provide a novel brake actuating mechanism forming a part of a trailer hitch having an easily operated, yet positive and rugged means for insuring the optimum amount of braking at all times.

A further object of this invention is to provide novel means for adjusting the brake actuator when the trailer is accidentally detached from the towing vehicle.

Since the trailer will tend to override the towing vehicle when the two are driven in a reverse direction, or backed up, provision must be made to prevent the brakes from engaging under such circumstances. AC- cordingly, another object of this invention is the provision of automatic brake release means which may be used when it is desired to back the trailer and the vehicle pulling the trailer.

The tow bar is connected to the trailer tongue by means of links, which, with the tow bar and tongue, form a parallelogram. When relative movement takes place be tween the trailer and the towing vehicle, the tongue and the tow bar, because of the parallelogram arrangement, remain parallel. The usual practice has been to place the tongue below the tow bar. However, since the device described below has an adjusting mechanism and pivot for the piston rod placed on the tow bar, it has been found advantageous to place the tow bar underneath the tongue. By making the tow bar underslung in this way, otherwise complex construction is overcome. Moreover, an unsightly appearance and bulky construction are avoided.

Therefore, it is a still further object of this invention to provide a trailer brake actuating mechanism located on the trailer tongue and the tow bar, having an adjusting device for the piston actuator, in which the tow bar is placed under the trailer tongue.

Other objects and advantages reside in the construction of parts, the combination thereof, the method of manufacture and the mode of operation, as will become more apparent from the following description.

Referring to the drawings,

FIGURE 1 is a side elevational view which shows the relationship between the novel trailer bitch and brake actuator, the trailer and the automobile which pulls the trailer. For clarity, some parts of the brake actuator are omitted.

FIGURE 2 is a side elevational view, with parts broken away, of the portion of FIGURE 1 within the oval 2, showing on a large scale the novel hitch and brake actuator structure.

FIGURE 3 is an enlarged sectional view, taken substantially on line 33 of FIGURE 2.

FIGURE 4 is another enlarged sectional view, taken substantially on line d4- of FIGURE 2.

FIGURE 5 is a portion of the brake cylinder in section and parts associated therewith.

FIGURE 6 is an enlarged, fragmentary view of a portion of the apparatus of FIGURE 2.

In FIGURE 1 the hitch H is shown as providing a connection between a towing automobile A and a trailer T. A hollow tongue 10 connected to the trailer T rigidly supports a channel member 12. Channel 12 is connected to a tow bar 16 which, in turn, is connected to the automobile A at 18.

Referring to FIGURES 2-4, it is seen that links 14 and 15 are connected to channel member 12 by means of bolts 20 and Zn passed through depending brackets 21 and 21' integral with or welded to channel member 12. Links 14 and 15 are connected to tow bar 16 by means of bolts 22 and 22' passed through brackets 23 and 23 integral with or welded to a plate 24 which is bolted, as at 26, to the bottom portion of tow bar 15. Connection 13 comprises a conventional ball and socket arrangement which may be released by loosening bolt 28. To restrain relative motive between the hollow tongue It and to tow bar 16, a dashpot or shock absorber 38 is provided between those members. Dashpot 38 has one end connected to a bracket 34 and the other end connected to an extended portion 14a of the link 14. The bracket 34 is secured to the tongue 16 by bolts 36. By this arrangement, it can be readily seen that the relative movement of the ends of the dashpot is greater than the relative movement of the tongue 16 with respect to the tow bar 16. The dashpot 38 deters or resists relative movement between the tongue 19 and the tow bar 16.

As can be readily seen in FIGURE 2, the dashpot being mounted on the end of the link 14 below the point where the link 14 is attached to member 24, the stroke of the dashpot or shock absorber is greater than the relative movement between the tongue it) and the tow bar 16. There are two advantages to this arrangement. The stroke of the dashpot or shock absorber, in addition .to being greater than the relative movement between the tongue 10 and the tow bar 16, also results in the shock absorber being more effective than if it were connected directly between the tongue 10 and the tow bar 16. The shock absorber, being attached to the extreme end of the link 14, results in an advantageous leverage as far as the shock absorber is concerned.

The parts described form a complete connection or hitch between the automobile A and the trailer T. When in motion, the parts are in approximately the full line position shown in FIGURE 2. The dashpot or shock absorber 38 serves to prevent relative motion between the trailer and the automobile and keeps the trailer from hunting. Further means are provided to restrain relafollows.

tive motion between the tongue it) and the tow bar In, which means also serve as the actuator for hydraulic brakes contained in the trailer. This means will now be described in detail.

A pair of plates 42 is secured to the channel member 12 by welding, or in any other suitable manner. Plates 42 support therebetween a housing 44 for a conventional hydraulic cylinder and reservoir by means of bolt 4-6 which passes through openings 43 in housing 44. As shown best in FIGURE 5, housing 4-4 is dividedinto two sections by a wall 5%, the upper section 52 forming a reservoir, the lower section 5 being a cylinder which houses a piston 55 having a rubber cup-shaped gasket 58 and a spring 6%; which opposes movement of piston 56. Piston 56 is also provided with a conical extension 88 surrounded at one end by an annular bushing 8 to keep the piston accurately centered within the cylinder. Cap 53 is provided to insure ready access to reservoir 52 for checking the fluid level and for adding fluid if necessary. Conveniently, cap 53 extends through opening 53a in channel member 12. Control vents 62; and as provide communication between the reservoir portion 52 and the cylinder portion 5 3- of the housing. One end 66 of the housing is provided with a hydraulic connection 68 having an outlet 63a and a conduit 76 which passes through the hollow tongue lit to a brake mechanism (not shown in the trailer. As will be apparent to those familiar with the art, movement of piston 56 to the left, as viewed in FIGURE 5, or conversely movement of cylinder id to the right, so that the cup-shaped gasket portion 53 extends to the left of the vent 62, will force hydraulic fluid through conduit 7% to the hydraulic brake mechanism in the trailer.

A piston rod 72 is attached to the piston 56. .This piston rod passes through a resilient cup-shaped member 74 attached to an annular flange 76 on the housing 44. An annular recess 8% near the end of the flange '75 receives a rib 78 projecting inwardly at the end of the cup-shaped member 74. The cup-shaped member '74 acts as a dust cover, keeping out dust and other foreign material from the piston and the cylinder.

The end of the piston rod 72 projects into a tubular sleeve 73 and is fixedly secured thereto, so that the tubular sleeve and the rod 72 always move together. The opposite end of the tubular sleeve 73 has mounted therein a rod 75 adjustably connected to a lug 77 pivotally attached to the tow bar 1d. The rod 75 is slidably mounted in the end of the tubular sleeve '73 and abuts the end of the rod 72 when the distance between the towing vehicle and the trailer is decreased by the inertia of the trailer. When the trailer is towed, the end of the rod 75 is spaced from the end of the rod '72, as clearly shown in dotted outline in FIGURE 2. The trailer may advance towards the towing vehicle a distance sulficient to close the gap between the end of the rod 75 and the end of the rod 72 without actuating the rod 72. This constitutes a lost motion mechanism. Thus, when the trailer advances towards the towing vehicle and when the gap between the rod 75 and the rod '72 has been closed, the rod 75 engages the end of the rod 72 to actuate the piston within the cylinder 54. In so doing, hydraulic fluid is supplied to the brakes.

The operation of the device thus far described is as When in motion, the parts are in the full line position, as shown in FIGURE 2. However, if it is necessary to stop or retard the motion of the automobile, or to descend a hill, the inertia of the trailer tends to move it toward the automobile. This causes the tongue id and channel member 12 to move forward with respect to the tow bar 16 and take the position shown by the dotted lines shown in FIGURE 2, indicating the position of members 12, 14 and 74. At the same time, housing 44, which is rigidly connected to channel member 12, also moves forward, while piston 56 is actuated or moved to brake applying position by the piston rod 72, the tubular sleeve 73 and the lug 77 actuated by the tow bar is. After a predetermined amount of movement of housing 44 and its cylinder 58 with respect to the piston 56, bydraulic fluid is forced through the conduit 70 to apply the hydraulic brake mechanism within trailer T. Once the trailer speed is retarded sufficiently by the brakes, the parts will return to the full line position shown in FIGURE 2 and the pressure on the hydraulic brakes in the trailer will be removed. If the trailer, the tongue 10 and the channel 12 again override the tow bar 16, the raking process will repeat itself.

Any tendency of the trailer to hunt or jerk during the stopping process just outlined will be offset or restrained due to the shock absorber 38 and the cushioning provided by the hydraulic fluid, part of which occupies the space 86 behind piston 56 when the piston is actuated to the left, as shown in FIGURE 5. The lateral separation between channel member 12 and plate orbar 24 will vary slightly as the channel member overrides the bar 24-. However, this has no effect on the operation of the piston rod 72 and piston 56, since the second rod is pivoted to the tow bar 16 and the resilient or flexible cup 74 allows for movement of the rod 72. Extension 88, being conical, likewise does not interefere with pivotal movement of piston rod 72.

In the event the hitch is broken or the hitch should become detached from the towing vehicle, as for example if member 28 is loosened so as to release the hitch from the tow bar on the towing vehicle, the brake should then be applied to the towing vehicle so as to prevent an accident. This has been accomplished by means of a breakaway brake mechanism. The lever 90 is connected by a chain or cable 91 to the towing vehicle. This chain or cable has sufiicient strength to actuate the lever 90, but not sufiicient strength to tow the trailer. Safety chains 93 are used as a precautionary measure to prevent the trailer from being detached from the towing vehicle in case the hitch fails for any reason whatsoever. The chains 93 are sufiiciently strong to tow the towing vehicle.

The lever 9%) is pivotally mounted upon a pin 92 fixedly secured to a pair of brackets 95 and 97. These brackets are fixedly secured to the channel 112. A pair of members or lugs 94, integral with the lever 93, engage a flange 73a fixedly attached to the tubular sleeve 73. As the lever 90 is rotated in a clockwise direction, as viewed in FIGURE 2, members 94 actuate the flange 73a and with it the tubular sleeve 73 and the piston rod 72, to apply the brakes to the trailer before the chain 91 snaps or breaks. As the brakes are applied to the trailer and the towing vehicle continues to travel, the application of the brakes will increase the force required to tow the towing vehicle to cause the chain 91 to break, at which time the safety chains 93 tow the trailer independently of the hitch. Being the brakes have been set on the trailer and if there is sufiicient load on the trailer to create sufiicient friction between the trailer wheels and the pavement, the trailer brakes may be sufficiently strong to arrest the movement of the towing vehicle. In actual tests, the brakes on the trailer have been sufficiently strong to stop a coasting automobile used as a towing vehicle in a very short distance. As the lever 90 is rotated in a clockwise direction, a ratchet 104 integral with the lever is also rotated in a clockwise direction. A pawl N2 engages the ratchet and locks it in position. This pawl is pivotally supported by the wall 1611 through a pivot pin 103 and is urged into engagement with the ratchet by a spring 1% resting upon a flange 97a integral with the bracket 97. That being the case, when the lever 90 has been rotated in a doc"- wise direction, it, so to speak, locks the hydraulic brakes in braking position.

In the event it is desired to back the automobile, it is obvious that the trailer would again tend to override the tow bar 16, thereby actuating the trailer brakes. To prevent the brakes from being actuated under such circumstances, a bypass valve for the hydraulic fluid is prosneasao yided. This valve is shown at 103 in FIGURE 5 and conduit 116 into the reservoir 52.

After backing the trailer and it is desired to move forward, the electromagnetic valve 1&8 will automatically close upon de-energizing the back-up lights. If the piston is to the left of vents62 and 64 when the valve is closed, there will be fluid on the right side of piston 56 within cavity 36. However, this position of the piston will not prevent the trailer from moving forward, since the piston will return to the right, as viewed in FIGURES. This is possible, not only because some of the fluid will be returned to reservoir 52 through vents 62 and 64, but also, the rim of the cup-shaped gasket 58 will flex, permitting fluid to enter the left cylinder portion 54.

Thus, the device described herein provides a compact, positive and re iable braking actuator havingprovisions for allowing for reversal of the trailer without external control.

'ihisapplication is a continuation of our copending application, Serial No. 326,821, now abandoned.

Although the preferred embodiment of the device has been described, it will be understood that within the purview of this invention various changes may be made in the form, details, proportion and arrangement of parts, the combination thereof andmode of operation, which generally stated consist in a device capable of carrying out the other and away from one another, a hydraulic cylinder having a piston therein, said cylinder being mounted on one of said members, said piston being movable in said cylinder and capable of supplying brake fluid under pressure to actuate the brake mechanism, piston rod means connected to said piston, link means for pivotally connecting said piston rod means directly to the other of said members tending to cause movement of said piston rod means at least equal to the movement of said members toward one another, said piston rod means being movable independently of said link means in a direction away from said link means, whereby said piston can be actuated through said piston rod means independently of said link means and independently of the relative movement of said two members, and emergency means for moving said piston to actuate said brake mechanism in the event of a break-away of said tow bar member, said emergency means including a lever, flexible means adapted to connect said lever to the towing vehicle independently of said tow bar member, means pivotally connecting said lever to the member on which said cylinder ismounted, flange means functionally integral with said piston rod means, said lever being positioned tocontact said flange means directly and to actuate said piston rod means, the independent movement of said link means and said piston rod means enabling said piston rod means to move toward said cylinder independently of the relative movement of said two members, independently of said connecting means, and independently of said shock absorber means, when said lever is moved by said flexible means, a ratchet aiiixed to one of said lever and the member to which said lever is attached, a pawl aflixed to the other of said lever and the member towhich said lever is attached and engageable with said ratchet in all positions of said lever, and a spring engaged-with the same one of said leverand the member as said pawl to urge said pawl toward said ratchet to prevent the return of said lever to its original position after being moved by said flexible means.

References Cited in the file of this patent UNITED STATES PATENTS 1,896,427 Selvester Feb. 7, 1933 2,101,600 Sandul Dec. 7, 1937 2,135,097 Billingsley Nov. 1, 1938 2,211,025 Parkes Q. Aug. 13, 1940 2,846,030 Wade Aug fi, 1958 2,954,104 Shumate Sept. 27. 1960 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,168 ,940 February 9, 1965 James 0. Ross et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 31, for "shown" read show column 2, line 15, for "large" read larger line 41, for "motive" read motion line 42, for "to" read the column 3,

line 27 after "shown" insert a closing p renthesis Signed and sealed this 3rd day of August 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

